Method, Component and Structure for Constructing a Dual-Use Staircase

ABSTRACT

A method of converting a traditional staircase into a dual-use staircase, for reducing the stepping height and knee stress in stairs climbing and descending, comprises: providing a plurality of lifting modules and a plurality of extending modules; connecting the plurality of lifting and extending modules in pairs to the original steps respectively; and optionally connecting a plurality of dividers in between said lifting and extending modules respectively. 
     The dual-use staircase structure reduces the step rise by half, while keeping the total run about the same. It allows healthy people to walk in a full-step domain, while allowing people with knee concerns to walk on a half-step domain. The dual-use staircase may include dividers with lateral openings to facilitate reverse turning halfway during ascending or descending of the staircase.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application claims priority to U.S. Provisional Patent Application No. 61/316,448 filed on Mar. 23, 2010, the complete disclosure of which is incorporated by reference in its entirety.

FIELD OF THE INVENTION

The invention is related to a method and structure of modifying an existing traditional staircase for easier climbing and descending with reduced stress on the knee.

BACKGROUND OF THE INVENTION

A traditional staircase with a hand rail on the left is illustrated in FIG. 1; wherein each step 10 including a tread (or stepping surface) 10 a and a riser 10 b. The risers can be vertical or slightly tilted, and they can be missing to become an “open” stair structure. A cross-sectional view of the staircase and relevant measurements are shown in FIG. 2. Each step is measured by a vertical “rise” and a horizontal “run” or “depth.” A “rise” or “rise height” is the difference in height between the top surfaces of two adjacent steps. A “run” is a horizontal displacement between two outer edges of adjacent steps. A “depth” is another horizontal measurement from the outer edge of a step to the inner edge of the step (which can be the bottom edge of the riser of a next upper step). The “total rise” between the upper and lower levels and the “total run” between the outer edges of the first and last steps are also illustrated. An inward direction is a horizontal forward moving direction during climbing, and an outward direction is the reverse of the inward direction. A slope Z110 of a staircase is the angle of inclination for the pitch line (along the tips of the outer edges of the treads), measured in degrees from the horizontal line, as shown in FIG. 2.

It is well known that walking up or down stairs may cause knee stress and knee pain to certain people. Some healthy elder may comfortably walk around on a flat level, but starts feeling pain in stairs climbing or descending. There were reports showing that walking down a stair can cause more stress on the knee than going up, as the body weight, the step height and the gravity all working together to aggravate the stress on the knee.

There is a comfortable range of the depth and rise of each step for a staircase. The depth is related to the size (length) of a foot, the rise related to a vertical range for raising and dropping a foot with reasonable effort. Examples of typical range of staircase parameters for daily walking of healthy people are: about 6″ to 8¼″ for step rise, about 8¼″ to 11″ or more for step run or depth, less than 45 degrees preferably less than 40 or even 35 degrees) for inclination angle. There are also various guidelines specified in building codes of different countries, but typically within the above range. For some elders or persons with a knee concern, commonly used traditional staircases such as within the above common stairs parameter range still may cause stress and discomfort.

For a tight space the slope of a traditional staircase can become very steep, and the outer portion of an upper tread may substantially overlap with the inner portion of a lower tread. In this case, a toe or a foot may easily get caught at an intermediate step level while walking on the staircase. Especially, when climbing up, a foot needs to retreat first before stepping forward, and descending facing forward (in a typical back-to-the staircase manner) is even more difficult. This steep-slope stairs issue is pronounced at a slope larger than 50 or 60 degrees. It causes difficulty in stairs climbing or descending even for healthy people. And prior-art alternating tread stairs are known to address this issue.

U.S. Pat. Nos. 4,509,617 and 4,981,195 each described a stair having alternate half treads, supported by a central stringer and two parallel side stringers. The half treads on one side of the central stringer alternate with those on the other side of the central stringer. It may be regarded as a traditional staircase with alternatively retreated (or totally disappeared) half treads, such that when walking up or down, a foot will not easily get caught in an intermediate step level due to the openings created by the retreated or disappeared half treads. On the other hand, there are safety concerns of existing alternating tread stairs. A central stringer is a safety issue if making a turn halfway during ascending or descending, as a foot needs to be raised and dropped from one side to another, or a foot may slip over the top edge of the inclined central stringer. If without a central stringer, the sharp inner corners of the half treads further pose a safety threat. In addition, the walking pattern is more complex than traditional staircase. As a result, alternating tread stairs have limited use even for healthy people, primarily for tight-space or steep-inclination applications, such as attic, roof or equipment access, or where one would use a fixed ladder instead.

Neither the traditional-staircase nor the alternating-tread-staircase prior arts have described or suggested a simple method for constructing or modifying a main staircase between floors, suitable for daily use of the whole family members including those with knee concerns. A solution is thus needed for a dual-use staircase to allow a family member with knee concerns to walk in a gentle pace, while allowing other family members to walk in a rapid or regular pace, for daily stairs climbing and descending.

SUMMARY OF THE INVENTION

Easier stair climbing and descending can be achieved by: reducing the step rise of a traditional staircase, which results in less knee bending and hence reduced knee stress. The challenges include keeping the same tread depth and about the same total run.

To accommodate the needs of family members, with or without knee-stress concern in stair climbing or descending, an existing traditional staircase can be modified and converted to meet the needs of both.

Add-on parts can be provided to raise a first portion of a tread about half a rise, and to extend a second adjacent portion of the tread outwards about half a step depth. An array of said second portions from each step forms a full-step domain (FSD), with a commonly-used and comfortable step rise, step depth and stairs inclination angle, suitable for house members without knee issues to walk in regular pace. Another array of the first portions, combining with adjacent parts of the second portions, form a half-step domain (HSD), suitable for house members with knee concerns to walk in a half-rise, half-run, gentle pattern.

Alternatively, an original staircase can be fabricated with a pre-cut cavities, about half rise and half depth measured from a step nose (outer edge), for a portion of the width of each step. This allows easy modification of the staircase as a dual-use staircase for reducing stress in climbing and descending.

Dividers, preferably arranged with a number of lateral (or sideway) openings, serve as a blocking barrier to avoid a person walking in the FSD from wandering into the HSD, while allowing a comfortable turn halfway during climbing or descending in the HSD based a lateral opening design.

The present invention provides a viable alternative solution for reducing knee stress in stairs climbing and descending without adopting a more expensive and power-consuming solutions like elevator, escalator or chair lift.

Accordingly, a first objective of the invention is to provide a method and structure, for converting an existing traditional staircase, such that the stepping rise and knee stress can be reduced while keeping the total run about the same.

A second objective of the invention is to allow co-existing of a full-step domain and a half-step domain, in a dual-use staircase, such that persons without any knee problem may comfortably and efficiently walk in the full-step domain, while persons with knee concerns may walk in a gentle half-step domain.

A third objective of the invention is provide an improved divider structure for the dual-use staircase structure, to avoid persons walking in the full-step domain wandering into the half-step domain, and to allow a person walking in the half-step domain making a comfortable turn halfway during climbing or descending.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a three-dimensional (3-D) view of a traditional staircase;

FIG. 2 shows a cross-section view of a traditional staircase with stairs-related definitions and directions defined;

FIG. 3 shows a 3-D view of a dual-use staircase based on the first preferred implementation method;

FIG. 4A shows a cross-section view of the dual-use staircase of FIG. 2 along the lifting modules;

FIG. 4B shows a cross-section view of the dual-use staircase of FIG. 2 along the extending modules;

FIG. 5 shows a side-view of the dual-use staircase of FIG. 2;

FIG. 6 shows a 3-D diagram of a dual-use staircase, and dividers with lateral openings;

FIG. 7A shows a side view of a divider with a convex rounded edge;

FIG. 7B shows a side view of a divider with a slant edge;

FIG. 7C shows a side view of a divider with a concave rounded edge;

FIG. 8 shows a 3-D view of a traditional staircase being modified with a first lifting module and a first extending module, which is connected to a first connector base from underneath;

FIG. 9 shows a 3-D view of a traditional staircase being modified with a second lifting module and a second extending module, which is connected to the first connector base of FIG. 8 from above;

FIG. 10 shows a 3-D view of a traditional staircase being converted to a dual-use staircase with certain surface covering;

FIG. 11 illustrates a cross-section view of a dual-use staircase along the lifting modules with depth adjustability and surface covering;

FIG. 12A illustrates a lifting module with a first exampled depth- and height-adjusting method and elements;

FIG. 12B illustrates a lifting module with a second exampled depth- and height-adjusting method and elements;

FIG. 13 illustrates an extending module with an exampled depth- and height-adjusting methods and components;

FIG. 14A illustrates a cross-section view of a dual-use staircase along the extending modules with depth- and height-adjustability and tread surface covering;

FIG. 14B shows a cross-section view of adjacent extending modules connected by a connector base with adjustable depth positions;

FIG. 15 shows a cross-section view of adjacent (or paired) lifting and extending modules connected to each other and also connected to an upper and a lower connector base, using pins and pin holes as a connection example;

FIG. 16 shows a 3-D view of a dual-use staircase with a turn and an intermediate platform. Optional dividers were not included in the illustration.

FIG. 17 shows a 3-D view of a dual-use staircase modified from a traditional staircase with a partial-width implementation;

FIG. 18 shows a basic flow chart illustrating the steps of constructing a dual-use staircase according to the first preferred implementation method;

FIG. 19 shows an implementation flow chart related to FIG. 18, illustrating the steps of constructing a dual-use staircase based on a plurality of lifting and extending modules;

FIG. 20 shows a 3-D view of stair steps with cavities according to the second preferred implementation method for a dual-use staircase;

FIG. 21 shows a 3-D view of stair steps with cavities and adjacent annex modules according to the second preferred implementation method for a dual-use staircase;

FIG. 22 shows a 3-D view of a completed dual-use staircase according to the second preferred implementation method;

FIG. 23 shows a basic flow chart illustrating the steps of constructing a dual-use staircase according to the second preferred implementation method.

DETAILED DESCRIPTION OF THE PREFERRED METHODS AND EMBODIMENTS

A first preferred embodiment for converting a traditional staircase 110 into a dual-use staircase 100 is illustrated in FIG. 3 in view of FIG. 1.

The traditional staircase 110 includes a plurality of N original steps 111 of a full width W1, each original step has an original tread 111 b, an original depth (or first depth) D1 and an original rise (or first height) H1. A first portion of the stepping surface of the ith original tread 111 b is raised for a raised height H5 and thus forming a first adjusted tread 125 of a first partial width WS1, for i=1 to N−1. A second portion of the stepping surface of the jth original tread 111 b is extended outwards for an incremental depth D5 and thus forming a second adjusted tread 135 of a second partial width WS2, for j=1 to N. As shown in FIG. 3, the first and second adjusted treads are adjacent to each other and each being lined up to form a first and second arrays of alternating stepping surfaces respectively. In addition, an adjacent portion of a stepping surface of the ground floor adjacent to the first adjusted tread 125 of the first-stage original step is also raised for another raised height H6.

The raised height H5 is within 35% to 65% (preferably about half) of the first height H1 of an adjacent original step; and the incremental depth D5 is within 35% to 65% (preferably about half) of the first depth D1 of an adjacent original step. Similarly, the raised height H6 is within 35% to 65% (preferably about half) of the first height H1 of the first-stage original step.

According to the first preferred embodiment, the methods of forming the first adjusted treads 125 and second adjusted treads 135 can be achieved by employing add-on parts including a plurality of lifting and extending modules as described in more details below.

As shown in FIG. 3, to the left near the hand rail 195 is an array of lifting modules 120 with a first partial width WS1 to support the first adjusted treads 125, to the right is another array of extending modules 130 with a width WS2 to support the second adjusted treads 135. Each lifting module 120 has a second height H2 and a second depth D2 as shown in FIG. 4A for supporting the first adjusted tread 125 as in FIG. 3. Each extending module 130 has a third height H3 and a third depth D3 is shown in FIG. 4B for supporting the second adjusted tread 135 as in FIG. 3.

As illustrated in FIGS. 4A and 4B, the second height H2 of a lifting module 120 is about half (or within 35% to 65%) of the first height H1 of an adjacent original step 111. The third depth D3 of an extending modules 130 is about half (or within 35% to 65%) of the first depth D1 of an adjacent original step 111. And the third height H3 of an extending module 130 is about matching (within a +/−5% tolerance) to the first height H1 of a neighboring original step 111. As an example, for a first height H1 of 7 inch to 8 inch, the second height H2 is preferably about half of H1 at 3.5 inch to 4 inch, thus greatly reducing the stepping height.

Preferably, the extending modules are wider than the lifting modules. The lifting module has a smaller width, sufficient for one foot of a first person to comfortably stepping on with a hip clearance to the hand rail. The extending module has a larger width, suitable for another foot of the first person and another person to step on simultaneously. Preferably, WS1 be in the range of 9.5 inch to 12 inch, alternatively in the range of 8¼ inch to 14 inch, with WS2>2×WS1. Accordingly, the first partial width WS1 is less than 40% of the full width W1 of an original step. Thus, with the hand rail still within reach, the array of second adjusted treads forms a full-step domain (FSD) for healthy people to walk up and down the stair in a regular pace. The array of first adjusted treads and the adjacent small portions of the second adjusted treads form a half-step domain (HSD), suitable for people with knee concerns to climb or descend with substantially reduced stepping height.

As an example, for walking up in the HSD, the left foot will step on a lifting module then the right foot will step on an adjacent portion of a next higher extending module. It can be easily seen, from the left step to the right step there is only half a rise and half a run stepping as compared to walking on the original staircase. Since the stress on a human knee can increase rapidly with the step rise and vice versa, the dual-use staircase thus greatly reduces the knee stress by cutting both the rise and stepping size in half. This is particularly beneficial for persons with knee-stress concerns or elders with limited motion capability. Once getting used to the new, dual-use staircase, walking up and down the stairs can become a comfortable and gentle exercise rather than a stressing routine.

FIG. 5 shows a side view of the dual-use staircase 100 of FIG. 3. A second outer edge 120 k is a nose edge of a lifting module 120, a third outer edge 130 k is a nose edge of an extending module 130. The third outer edges 130 k form a pitch line with a slope Z100, which is the slope of the dual-use staircase 100. Z100 should be about equal to the slope Z110 of the original staircase 110.

A plurality of dividers 140 connected in between extending modules 130 and lifting modules 120 respectively are also shown in FIGS. 3 and 5. The dividers 140 are lined up with a number of lateral openings 142 as in FIGS. 5 and 6. As a preferred exampled embodiment, a divider 140 having an upper edge 141 aligning with an edge of the upper surface (or first adjusted tread 125) of the lifting module 120, thus forming a lateral opening 142 along the edge of the first adjusted tread 125. The advantage of the dividers 140 with lateral openings 142 is clearly illustrated in FIG. 6. The solid arrow shows that dividers 140 serve as a barrier to keep a person walking on the FSD from wandering into the lifting modules 120 of the HSD, while the dashed arrow shows a foot on the lifting module 120 can move easily to the FSD without over raising the foot (across a divider) causing safety concern, or reversely move from the FSD to the lifting module 120 by only a half rise. This makes it safer to initiate or complete a turn halfway during ascending or descending of the dual-use staircase when needed. The dividers further serve as a natural foot guard to keep a person walking on the HSD on track.

FIGS. 7A, 7B and 7C show three preferred examples of divider 140. The dividers 140, 140′ and 140″ with upper edges 141, 141′ and 141″, include a convex, slant and convex outer edges respectively.

FIGS. 8 to 10 show lifting modules 120 and extending modules 130 being connected in pairs to the original steps 111 from bottom up. FIG. 8 illustrates the conventional staircase with the lowest original 111 step being modified with a first lifting module 120 and a first extending module 130 as a pair. A first connector base 150 being connected to and overlapped with a first original step 111, and also connected to the top of the first extending module 130. On the left portion of the connector base 150 is an optional extension for extending underneath, and connecting to, an adjacent lifting module 120. FIG. 9 shows a second extending module 130 and a second lifting module 120 being added and connected above the first connector base 150. Repeating the same steps, then adding tread surfaces over the lifting and extending modules to form first adjusted treads 125 and second adjusted treads 135, also adding optional dividers 140, one can see that a dual-use staircase can be formed as in FIG. 10.

The first and second adjusted treads 125 and 135 can be formed over a traditional staircase based on common raised floor architecture, and supported and connected by, for example, frames, frameworks, posts, floor levelers, etc. However, this involves custom fit works that may be time consuming since each original step 111 may not have identical dimensions even within the same original staircase. Alternatively, it can be built with pre-fabricated parts, preferably with adjustable dimensions and adjustable interconnecting positions.

FIGS. 11 to 16 illustrate exampled prefabricated add-on modification parts, including adjustable dimensions and interconnecting positions.

FIG. 11 shows a cross-section view of the modification parts, cutting through lifting modules 120. As a preferred embodiment, a lifting module 120 includes a first main support 121, an extendable part 122, and a stacking layer 171. The first main support is prefabricated in several predetermined dimensions, and one being shorter than a target step depth by less than 1.5 inch can be selected. With an optional extendable part 122, the lifting module 120 can better match a step depth of an original step 111.

As shown in FIG. 12A, an extendable part 122 can be partially housed in the first main support 121 for depth adjustability. Alternatively, filler material 124 can be attached to the first main support 121 as in FIG. 12B. The filler material is preferably easy to cut, shape or form, and can be less rigid than the first main support 121. To adjust the height of the main support, a stacking layer 171 or other height adjusters can be attached to the main support. As an example, a height adjuster may include a set of foot levelers 123 for height and level adjustment as illustrated in FIG. 12B. For finishing up, surface covering such as tread board, rise board, or carpet, vinyl, etc., can be used to cover the upper and front surfaces of the lifting modules 120.

Similarly, the extending modules may have height and depth adjustability. As shown in FIGS. 13 and 14A, extending module 130 include a second main support 131, a depth adjuster 132 and a height adjuster 133. An internal void between the second main support 131 and the height adjuster 133 can be filled with a stacking layer 172 for overall rigidness to support human weight. The depth adjuster 132 may include an extendable part, a filler part, or foot-leveler like structure 132′ (as in FIG. 14A) which is disposed horizontally at the back of the second main support. The height adjuster 133 can be an extendable part or a foot-leveler like structure, or it can be replaced by at least one stacking layer 172.

Also illustrated in FIGS. 11 and 14A are optional cushions 181 and 182, disposed over first adjusted treads 125 (of lifting modules 120) and second adjusted treads 135 (over extending modules 130) respectively. The cushions are preferably made of soft or resilient material for comfortable stepping, and preferably having a skid resistant surface. Further preferably, either the raised and the extended boards, or the cushions over them, have curved surfaces for better ergonomics in stair climbing or descending. An example of a cushion with a curved surface, in this example a convex one, is shown in the cross-section views FIGS. 12 and 14.

As illustrated in FIGS. 14A and 14B, the connector base 150 serves to connect an upper and a lower extending module 130, and also connecting to an adjacent original step 111 for overall rigidness of the dual-use staircase. As illustrated, pins 151 and 151′ pairing with pin holes 152 and 152′ are examples of embodiment for rigid connection while allowing adjustable positioning. As shown in FIG. 14B, there is an exposed upper surface of the connector base 150 for forming a second adjusted tread 135 with or without another covering tread board. The connector base 150 with optional stacking layer 172 underneath may adhere to an original step 111 through removable adhesion method such as using adhesion tape, double-stick tape, self-adhesive surface, etc. And limited use of hard connection components (such as using screws 155 or nails) as in FIG. 15 may improve the overall sturdiness of the structure.

As shown in FIG. 15, adjacent extending modules 130 and lifting modules 120 can be connected directly or optionally connected through connector bases 150. A connector base 150 extending underneath a lifting module 120 is optional. Furthermore, a connector base is a rigid structure suitable for connecting various add-on parts and preferably also allowing attachment to original steps 111. A connector base is not limited to being shaped as a board-like structure. It can also be a framework like structure for connecting at least a lifting module, an extending module or their combinations. And the connection method may include pins and pin holes, tongues and grooves, screws, nails, etc. A connector base may include a wood board, a metal frame, a stiff film, a plastic piece, a male or female connection fixture, or combinations thereof.

FIG. 16 illustrates a dual-use staircase with an intermediate platform. Lifting modules 120, extending modules 130, first adjusted treads 125 and second adjusted treads 135 are as illustrated. In a preferred embodiment, a lifting module 120 with a rounded edge is disposed at an inner corner of the platform adjacent to a hand rail. Optional dividers such as those of FIGS. 6, 7A, 7B and 7C can also be included.

FIG. 17 illustrates a dual-use staircase with partial-width implementation. Exampled parts for modification are shown including lifting modules 120′, extending modules 130′, first adjusted treads 125′ each with a first partial width WS1, and second adjusted treads 135′ with a second partial width WS2. In this case, a substantial portion of the original steps 111 (with a full width W1) is not modified for material savings. Preferably, (WS1+WS2)<(W1×60%). The third depth D3 of the extending module 130′ can be less than half a first depth D1 of the original step 111, for reducing the nose-line difference D6 between the original step 111 and the extending module 130′ within the same step. Optionally, a riser surface of the extending module 130 may be slanted inwards as illustrated, for increasing the depth of the extending modules for easier stepping. Again, optional dividers can also be included (not shown).

FIG. 18 illustrates a basic method of converting a dual-use staircase from a traditional staircase.

FIG. 19 illustrates a first embodiment method for constructing a dual-use staircase based on connecting a plurality of lifting and extending modules to the original steps of a traditional staircase.

A second implementation method for constructing a dual-use staircase involves cutting a half-height/half-depth cavity for a small portion (width) of a step. As will be illustrated in more details in FIGS. 20 to 22, an additional annex module 128 can be used to extend a stepping surface of the cavity, forming an offset tread for easier climbing and descending.

FIG. 20 shows a staircase with a cavity 112 formed at an outer edge of original step 111 b″, preferably for a fraction of less than 40% of the full width of the original step. The original staircase has a typical rise R and depth D in each step. Each cavity is about a 0.5R in height vertically and 0.5D in depth horizontally.

FIG. 21 shows an annex module 128, about 0.5R in height and 0.5D in depth being added to extend the stepping surface of the cavity 128 for forming an offset step.

FIG. 22 shows a completed dual-use staircase from FIGS. 20 and 21, with offset treads 125″ and riser boards 126 covering the upper and front surfaces of the offset steps, a hand rail and optional dividers are also illustrated. In this case, the offset treads 125″ and adjacent portions of original treads 111 b″ form an HSD of alternating steps for reduced-step-height walking. And the portions of original treads 125″ (to the right of the cavities 112) form a FSD for regular and efficient walking of the staircase. FIG. 23 illustrates a second embodiment method for constructing a dual-use staircase based on forming cavities within original steps.

Furthermore, preferably the add-on parts as described use inter-locking attachment design including, for example, concealed fastening, grooves or rails for snapped-on, slide-in or screw-tight attachment. Preferably, the lifting and extending modules of multiple or all steps are interconnected together for overall strength and sturdiness of the dual-use staircase. The foot levelers of the main supports of lifting or extending modules can be glued to the existing treads of a conventional staircase with strong bonding while allowing later removal. It is also preferred that the add-on parts and interconnection fixtures allow later removal for easy restoration of a dual-use staircase to its original state. 

1. A method of converting a traditional staircase into a dual-use staircase, the traditional staircase having a plurality of N original steps, each original step having a first tread, a first depth and a first height, comprising: raising a first portion of the first tread for a first raised height and thus forming a first adjusted tread of the ith original step, for i=1 to N−1; extending a second portion of the first tread outwards for a first extended depth and thus forming a second adjusted tread of the jth original step, for j=1 to N; wherein said first adjusted treads being lined up and forming a first array of stepping surfaces; said second adjusted treads being lined up and forming a second array of stepping surfaces; and the first array being adjacent to the second array.
 2. The method of claim 1, further comprising: raising an adjacent portion of a stepping surface of a lower-level floor for a second raised height; wherein the adjacent portion being adjacent to the first adjusted tread; the second raised height being within 35% to 65% of the first height of the first original step; and the first raised height of the ith original step being within 35% to 65% of the first height of the (i+1)th original step; wherein 0<i<N.
 3. The method of claim 1, wherein the first extended depth of the jth original step being within 35% to 65% of the first depth of the (j−1)th original step; wherein 0<j<N+1.
 4. The method of claim 1, wherein the step of forming the second adjusted tread including disposing another tread partially overlapping the first tread and extending outwards for the first extended depth.
 5. A method of converting a traditional staircase into a dual-use staircase, the traditional staircase having a plurality of original steps, each original step having a first tread, a first depth and a first height, comprising: providing a plurality of lifting modules for connecting to the original steps respectively, wherein each lifting module having a second height less than the first height; providing a plurality of extending modules for connecting to the original steps respectively, wherein each extending module having a third height matching the first height within a 5% tolerance and having a third depth less than the first depth; and connecting the plurality of lifting and extending modules in pairs to the original steps respectively.
 6. The method of claim 5, wherein each second height being within 35% to 65% of the first height of an adjacent original step; and each third depth being within 35% to 65% of the first depth of an adjacent original step.
 7. The method of claim 5, wherein each lifting module including at least one of a first main support, a first height adjuster, a stacking layer or their combinations for adjusting said second height.
 8. The method of claim 5, wherein each extending module including at least one of a second main support, a depth adjuster, an extendable part or their combinations for adjusting said second depth.
 9. The method of claim 5, wherein the original steps having a full with W1; the lifting modules having a first partial width WS1; the extending modules having a second partial width WS2; and WS1<(W1×40%).
 10. The method of claim 5, wherein the original steps having a full with W1; the lifting modules having a first partial width WS1; the extending modules having a second partial width WS2; and (WS1+WS2)<(W1×60%).
 11. The method of claim 5, further comprising: connecting a plurality of connector bases to said original steps respectively; and connecting each connector base to at least one of said extending modules, lifting modules or their combinations.
 12. The method of claim 11, wherein the step of connecting each connector base to at least one of said extending modules, lifting modules or their combinations including using at least one of pins, pin holes, tongues, grooves, or their combinations for the connection.
 13. The method of claim 5, further comprising: connecting a plurality of dividers in between said extending and lifting modules respectively.
 14. The method of claim 13, wherein the plurality of dividers being lined up and forming at least one lateral opening.
 15. A method of converting a traditional staircase into a dual-use staircase, the traditional staircase having a plurality of original steps, each original step having a first tread with an outer edge, a first depth, a first width and a first height, comprising: forming a cavity in each original step from a portion of the outer edge with dimensions of a second height downwards, a second depth inwards and a second width in a lateral direction; connecting a plurality of annex modules to said original steps next to the cavities respectively; wherein a third top surface of each annex module aligns with a second top surface of an adjacent cavity; and further comprising forming a second tread over each aligned second and third top surfaces.
 16. The method of claim 15, wherein for each original step, the second height being within 35% to 65% of the first height; and the second depth being within 35% to 65% of the first depth.
 17. The method of claim 15, wherein said second treads being lined up in an array; and for each original step, the second width being less than 40% of the first width.
 18. A set of components for converting a traditional staircase into a dual-use staircase, the traditional staircase having a plurality of original steps, each original step having a first tread, a first depth and a first height, comprising: a plurality of lifting modules for connecting to the original steps respectively, wherein each lifting module having a second height less than the first height of an adjacent original step; a plurality of extending modules for connecting to the original steps respectively, wherein each extending module having a third height matching the first height within a 5% tolerance, and having a third depth less than the first depth, of an adjacent original step; wherein the plurality of lifting and extending modules being formed for connecting to each other in pairs and for connecting to the original steps respectively.
 19. The set of components as in claim 18, further comprising: a plurality of connector bases for connecting said pairs of lifting and extending modules to the original steps respectively.
 20. The set of components as in claim 18, further comprising: a plurality of dividers for connecting in between said lifting and extending modules respectively. 